1. Field of the Invention
The present invention relates to the field of manufacture of display devices, and in particular to an ultra-slim bezel display panel.
2. The Related Arts
Liquid crystal displays (LCDs) have a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and are thus used widely. Most of the LCDs that are currently available in the market are backlighting LCDs, which comprise a liquid crystal display panel and a backlight module. The operation principle of the liquid crystal display panel is that liquid crystal molecules are arranged between two parallel glass substrates and electricity is applied to the glass substrates to control the liquid crystal molecules to change direction in order to refract out light from the backlight module to generate an image.
A liquid crystal display panel is generally made up of a color filter (CF) substrate, a thin-film transistor (TFT) substrate, liquid crystal (LC) interposed between the CF substrate and the TFT substrate, and sealant. The TFT substrate and the CF substrate are often each provided with a alignment film formed thereon. When put in contact with LC, the alignment film causes LC to generate a pre-tilt angle in a predetermined direction so as to provide the liquid crystal molecules with a carrying angle (wherein the value of the pre-tilt angle shows important influence on the driving voltage of TFT-LCD, contrast, response time, and view angle). The alignment film is usually made of a material selected from polyimide (PI) materials and is formed by coating a PI solution on a substrate.
With the progress of the display technology, the requirement of general consumers for consumer electronic products is no longer limited to functionality and also additionally asking for considerations regarding designs and aesthetics and good visual experience. For example, ultra-slim bezel products are currently prevailing and as the name suggests, an ultra-slim bezel is made by further narrowing down a bezel of a conventional TFT-LCD to thus expand the area of an active area (AA) thereby achieving upgraded visual experience and aesthetics of product design. In view of this, to challenge an even higher level of LCD panel design and manufacture, such as device preciseness and material performance compatibility, upgrading and improvement to a significant extent is thus necessary.
Accuracy of coating a PI solution is thus becoming important. This is because an ultra-slim bezel design is different from the prior art designs and the distance that the AA zone is spaced form an edge of a glass substrate is closer. In addition, during the coating process of the PI solution, factors, such as back flowing of PI after coating and accuracy control of film shrinkage after PI has been baked, must be considered. Once the accuracy of the PI coating at a peripheral area of a panel is not well controlled, PI on a circumferential area of an LCD panel may flow backward to the AA zone so as to cause a mura phenomenon (a phenomenon where brightness is not uniform) on a periphery of the AA zone. This would greatly affect the quality and yield rate of the panel.
In view of the above, manufacturers of the industry often intend to overcome the above problems through change of the design. Such as a color resist wall arranged outside the AA zone to control the phenomenon of PI backward flowing. This, to some extents, stiff suffers the same problem of non-uniform backward flowing of PI and mura may appear on the circumference of the panel.